Inaccurate?

Rockburst

(Shining South)

Evocation
Level: Druid 2, Cleric 3, Sorcerer 3, Wizard 3,
Components: V, S,
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: 20-ft.-radius burst
Duration: Instantaneous
Saving Throw: Reflex half or Fortitude negates; see text
Spell Resistance: No

You cause a stone object, with volume of at least 8 cubic feet, to explode.
Rock shards fly outward from the detonation, and all creatures within the area of the spell take 1d4 points of damage plus 1 point per caster level (maximum +15).
A successful Reflex save halves this damage.
A magic stone object, or a nonmagic stone object in the possession of another creature, gets a Fortitude save to negate the effect.
Creatures cannot be affected by rockburst.